An arrangement of this kind is disclosed in for instance U.S. Pat. No. 3,505,865 and relates to a device for measuring angular differences between two toothed wheels which are mounted on a rotatable shaft. Such an arrangement comprises two inductive transmitters, each of which cooperates with a toothed wheel to generate electrical signals which depend on the angular position in space of the toothed cog-wheel. A differentiating device is connected to the two transmitters and is adapted to measure the difference between two signals generated by the transmitter. The measuring technique which is accomplished through the system according to the just mentioned U.S. specification is consequently utilized in the transmitter arrangement according to the present invention.
In the system according to the above patent, the two wheels are massive and are mounted on the shaft by means of supporting rings which have to be carefully centered and fixed directly on the shaft by means of jaws. Such an installation is rather complicated and time-consuming, which has caused problems specifically if the installation has to be carried out on a ship's propeller shaft during the short time period when the ship is staying in harbour for loading or unloading of cargo. Consequently, demands have been made for an improved installation of the toothed wheels which can be carried out more rapidly and which does not unnecessarily prolong the ship's stay in harbour.